1. Field of the Invention
The present invention relates to a polymer functional film which is useful as an ion exchange membrane, a reverse osmosis membrane, a forward osmosis membrane, a gas separation membrane or the like, and to a method for producing the same.
2. Description of the Related Art
Regarding membranes having various functions as functional polymer membranes, an ion exchange membrane, a reverse osmosis membrane, a forward osmosis membrane, a gas separation membrane and the like are known.
For example, an ion exchange membrane is used in electrodeionization (EDI), continuous electrodeionization (CEDI), electrodialysis (ED), electrodialysis reversal (EDR), and the like.
Electrodeionization (EDI) is a water treatment process for removing ions from an aqueous liquid using an ion exchange membrane and electric potential in order to achieve ion transport. Unlike other water purification technologies such as conventional ion exchange, electrodeionization can be used to produce ultrapure water without requiring the use of chemical agents such as acids or caustic soda. Electrodialysis (ED) and electrodialysis reversal (EDR) are electrochemical separation processes of removing ions and the like from water and other fluids.
In regard to ion exchange membranes, research is being conducted on the improvements in electrical resistance of membranes (membrane resistance) (see, for example, Patent Document 1). Patent Document 1 describes an anion exchange membrane which uses a styrene-divinylbenzene copolymer as a crosslinking polymer.
However, JP2000-212306A has descriptions of the improvements in membrane resistance, but does not have descriptions on the coefficient of water permeability that is in a trade-off relationship with the membrane resistance.